1. Field of the Invention
The present invention pertains to an implantable intraocular lens and, more particularly, pertains to a hydrogel lens containing laminated zone of focus lens elements.
This lens relates to hydrogel lenses which have discrete areas which serve to bring impinging rays to a focus in a specific area of the focal plane. Such lenses are called zone of focus lenses and are particularly useful for implantation into the eye as a substitute for the natural lens since, in combination with the brain, they effectively replicate the ability of the natural lens to bring objects at varying distances to a sharp focus.
The invention relates specifically to a zone of focus lens in which the hydrogel lens is a laminated structure comprising a number of laminated planar or curved hydrogel elements. The incident rays are brought to a focus on a portion of the retina and are dependent on the number of lens elements traversed by the ray. The lens area common to each combination of laminated lens elements serves to bring the rays from a given object passing through the area to a focus on a predetermined region of the retina. By selecting various powers for the hydrogel lens element laminate areas, it is possible to have an object at a given distance brought to an acceptable focus by at least one of the lens element laminated areas. In this manner, an in-focus image or sharp image is created on a particular portion of the retina serviced by that area. It has been found that the processing of the image by the brain results in the selective consideration of the sharpest image and the virtual discard of the other out-of-focus images created by the areas.
2. Description of the Prior Art
Limited attempts to produce a lens having areas of varying powers have been made. There have been many attempts to produce implantable lenses which serve for both close and far seeing, similar to bifocal spectacles. In general, such lenses have been produced with two regions having different powers. The light which impinges on the retina passes through one region to the exclusion of the other. In such a system, only one region of the lens is used at a time and there is no accommodation of the brain to reject an out-of-focus image. Great care and accuracy must be used in the preoperative measurements since both the near and far powers must be accurately determined. Since the near and far powers are not specifically interrelated, the inventory requirements are compounded since a variety of near powers must be available for every far power.
Further, the rigid materials used for lenses have required relatively large incisions for implantation, but the post-operative recovery period is shorter when a small incision is made.
The present invention overcomes the disadvantages of the prior art by providing a hydrogel lens which includes two or more laminated lens elements where each hydrogel lens element is of a different power.